Selena Gomez hit the gym in a sports bra this afternoon, just hours after photos surfaced of her and Justin Bieber cuddling in public. It's gone from "just friends" to "maybe getting back together in the future" to full-on happening in a matter of days!

Although the "Come & Get It" songstress tried to move on with The Weeknd, her Bieber fever ultimately returned and is stronger than ever!

"Since things ended with Justin for good, any other guys that Selena dated were placeholders. All the other guys were just flings. Justin always had her heart and attention. He was always her soulmate and her one true love," a source dished to Us Weekly.

"She met The Weeknd and all that changed — she [could] see a future with him and [felt] different about him than the other flings. She [had] been happy with him but Justin always has the biggest piece of her heart. The situation is a heart string type of thing. She has to figure out what she wants," the source added.

As for JB, he's working overtime to win her back!

"Justin really wants to get back with Selena. He has been texting her nonstop and hangs out with her whenever he can," another insider revealed.